1. Field of the Invention
The invention relates to a device for and a method of cross-cutting a moving web using a knife cylinder having at least one cutting knife which rotates about an axis parallel to the cutting line.
2. Description of the Related Art
U.S. Pat. No. 6,360,640 discloses a method of cross-cutting a web using a knife cylinder. In order to vary the length of the cut products, i.e. vary the cut length, the knife cylinder is driven at a circumferential speed that differs from the web speed, except during cutting. In the case of small cut lengths or when the knife cylinder has a plurality of cutting knives distributed uniformly over the circumference, the speed change has to be completed during a small amount of circumferential travel. This requires high accelerations and powerful up-shifting, i.e. acceleration torque, of the drive motor. Consequently, this presents practical limitations when implemented.